The present invention generally relates to the field of embolic protection, and more particularly to endoluminal devices that can be used to provide embolic protection during a surgical procedure.
During various cardiothoracic, pulmonary, and vascular surgeries, including coronary artery bypass grafting, heart valve repair or replacement, atrial or ventricular septal defect repair, angioplasty, atherectomy, aneurysm repair, and pulmonary thrombectomy, or any other procedure that makes use of cardiopulmonary bypass, cannulation of a patient""s vessel(s) are often required to provide vascular access for delivery of various diagnostic and therapeutic devices. In a conventional approach, incisions generally made by a surgical blade are needed for introduction of medical device(s). For example, during coronary artery bypass grafting (CABG) surgeries, cardiopulmonary bypass is established by cannulation of the aorta to provide circulatory isolation of the heart and coronary blood vessels. Multiple incisions on the aorta may be required, i.e., one for insertion of the arterial cannula, another for insertion of a balloon occluder to provide coronary isolation from the peripheral vascular system, and another for insertion of an arterial filter to provide protection against distal embolization. Once the incisions are made on the aorta, the devices often remain in the aorta throughout the entire procedure despite only being used intermittently, e.g., the cardioplegia catheter.
Due to significant mortality and morbidity associated with the conventional CABG surgeries from the use of cardiopulmonary bypass for circulatory support and the traditional method of access by median sternotomy, minimally invasive concepts recently have been adopted to make cardiothoracic procedures less invasive. Minimally invasive alternatives include the minimally invasive direct CABG procedure in which the operation is performed through minimal access incisions, eliminating cardiopulmonary bypass. The second alternative is to perform the procedure through minimal access incisions, and cardiopulmonary support is instituted through an extra-thoracic approach, i.e., the port access approach. The third alternative is to perform the procedure on a beating heart which allows greater access for more extensive revascularization, i.e., the xe2x80x9coff pumpxe2x80x9d stemotomy approach. In any of the minimally invasive alternatives, the space allowed for multiple incisions and device insertion is limited.
The disadvantages associated with the conventional or minimally invasive approach are that (1) the current methods require bulky valves and plastic housings that interfere with a surgeon""s working space, thereby reducing the space available for the surgeon to perform procedures, and (2) the aorta is traumatized as a result of multiple incisions, which may result in aortic dissection, aortic wall hematoma, and/or embolization of calcium plaque from the aortic wall. The greater the aortic trauma, the higher the perioperative morbidity a patient will endure.
Accordingly, there is a need for devices and methods which provide access to a vessel or body cavity and allow introduction of medical instrument(s), such as an arterial filter, through a single incision with minimal blood loss and with maximum convenience for the physician.
The present invention provides a medical device for introducing a blood filter into a body tissue, such as a vessel, or cardiac tissue, for preventing distal embolization. Obturators are also provided for a traumatic insertion through an incision in body tissue.
In a first embodiment, the medical device comprises an elongate tubular member having a lumen between a proximal end and a distal end. A filter, having an obturator tip at its distal end, is slideably received within the lumen of the elongate tubular member. The obturator tip is shaped to rest against the distal end of the elongate tubular member when the filter is within the lumen of the elongate tubular member. The filter is capable being advanced distally beyond the distal end of the elongate tubular member after the device is inserted into a vessel. A distal region of the elongate tubular member may include a suture flange for securing the device onto a vessel. The proximal end of the elongate tubular member may include a hemostatic valve to minimize blood loss.
In another embodiment, the elongate tubular member is flexible, thereby allowing a physician to manipulate the device in crowded surgical space. The filter comprises an expansion frame having an attached filter mesh that is generally conical. The obturator tip is attached at the apex of the conical mesh. The obturator tip, which may be made of thermoplastic polymer, silicone, urethane, or other suitable material, may be olive-shaped or star-shaped. The expansion frame, which comprises a generally circular ring of a flexible material, e.g., nitinol, may be attached to an elongate member that extends through the lumen of the elongate tubular member, e.g., hypotube. An optional cantilever beam bisects the generally circular ring and attaches to the ring at a distal end.
In a first method of using the obturators and introducers described above for introduction of a blood filter, the filter is contracted and withdrawn into the lumen of the elongate tubular member so that the obturator tip rests against the distal end of the elongate tubular member. The obturator tip and the distal end of the elongate tubular member are inserted into a blood vessel, e.g., an aorta, after an incision is made on the vessel wall. A hemostatic valve mounted within the lumen of the introducer prevents blood loss. In certain embodiments, a suture flange is provided on the distal end of the introducer, and sutures can be placed on the flange to stabilize the device onto the body tissue. The filter and the obturator tip are then advanced beyond the distal end of the elongate tubular member. The filter is deployed in the vessel to prevent embolization of materials, such as atheromatous plaque, thrombus, or tissue debris generated during the procedure. Vascular surgeries, including coronary artery bypass grafting, heart valve repair or replacement, atrial or ventricular septal defect repair, angioplasty, atherectomy, aneurysm repair, and pulmonary thrombectomy, can then be performed after establishment of cardiopulmonary bypass. After completion of the surgical procedure, the filter and the captured embolic debris are withdrawn into the lumen of the elongate tubular member. The device is then removed from the vessel.
There are several advantages in using the device disclosed herein for performing arterial filtration during vascular surgeries. For example, the devices (1) are constructed of fewer parts, thereby allowing easy manipulation of the device, (2) are less bulky, thereby allowing the ease of use in a crowded surgical space, (3) have less manufacturing cost, (4) have a flexible delivery system that allows added flexibility for working in a limited space, (5) have a reduced outer diameter as compared with an introducer sheath adapted to receive a length of hypotube that carries a filter, and (6) eliminate the step of removing a separate obturator during use (a step that can cause blood loss).
Additional features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.